Methods and apparatus for power efficient broadcasting and communication systems

ABSTRACT

A method and apparatus for content multicasting and broadcasting and data unicasting in a broadband multicarrier wireless communication system. A base station is configured to transmit, and a mobile station is configured to receive, a sequence of consecutive frames. The frames comprise two types: frames containing time-frequency resources for content multicasting and broadcasting via a single frequency network, and frames containing time-frequency resources for data unicasting without the use of a single frequency network. The two types of frames are intermixed in accordance with an intermixing configuration pattern. The intermixing configuration pattern is indicated by a bit-map contained in a scheduling signal.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of, and incorporates by reference inits entirety, U.S. patent application Ser. No. 14/596,109, entitled“METHODS AND APPARATUS FOR POWER EFFICIENT BROADCASTING ANDCOMMUNICATION SYSTEMS”, filed on Jan. 13, 2015, which is a continuationof, and incorporates by reference in its entirety, U.S. patentapplication Ser. No. 13/712,848, entitled “METHODS AND APPARATUS FORPOWER EFFICIENT BROADCASTING AND COMMUNICATION SYSTEMS”, filed on Dec.12, 2012, now granted U.S. Pat. No. 8,934,394, which is a divisional of,and incorporates by reference in its entirety, U.S. patent applicationSer. No. 13/422,829, now granted U.S. Pat. No. 8,457,081, entitled“METHODS AND APPARATUS FOR POWER EFFICIENT BROADCASTING ANDCOMMUNICATION SYSTEMS”, filed on Mar. 16, 2012, which is a continuationof, and incorporates by reference in its entirety, U.S. patentapplication Ser. No. 11/571,469, now granted U.S. Pat. No. 8,155,098,entitled “METHODS AND APPARATUS FOR POWER EFFICIENT BROADCASTING ANDCOMMUNICATION SYSTEMS”, having a 371 date of Oct. 9, 2008, which is aNational Stage application of PCT/US06/22376, entitled “METHODS ANDAPPARATUS FOR POWER EFFICIENT BROADCASTING AND COMMUNICATION SYSTEMS”,filed on Jun. 6, 2006, which claims the benefit of U.S. ProvisionalPatent Application No. 60/688,937, entitled “METHODS AND APPARATUS FORPOWER EFFICIENT BROADCASTING AND COMMUNICATION SYSTEMS”, filed on Jun.9, 2005. This application relates to U.S. Provisional Patent ApplicationNos. 60/665,184 and 60/665,205, filed on Mar. 25, 2005.

TECHNICAL FIELD

The disclosed embodiments relate, in general, to wireless communicationand, in particular, to methods and apparatus for power efficient signalbroadcasting and communication.

BACKGROUND

As a wireless service to mobile users, the transmission of multimedia isbecoming as important as voice connectivity. It is forecasted thatmultimedia applications will include interactive data services such asgaming and internet access as well as on-demand video and audioservices.

Digital video and audio broadcasting and multicasting are one class ofwireless services. Some applications such as news-casting,sports-casting, and other types of multimedia entertainment require noor minimum interaction. The most efficient way to deliver these types ofmass multimedia contents is broadcasting. Given these broadband wirelessapplications, the platform for the next generation wirelesscommunications should deliver interactive data and broadcasting servicesat the same time. The design of such a platform with mixed applicationsmust be well balanced, optimizing quality of service, efficiency, powerconsumption by mobile stations, etc.

A mobile station in continuous reception of a video broadcasting streamconsumes significant amount of power, which becomes even a biggerchallenge if the mobile station is running on battery. Furthermore, whendata application traffic shares the same air link resource with thevideo streams, a video burst that utilizes the entire air link resourcewill cause a long delay for other applications such as for TransmissionControl Protocol (TCP). This can become a major problem if some controldata transmissions require swift responses, such as power control,hybrid automatic retransmission request (HARQ) feedback and channelquality information (CQI) measurement reports. The exclusive use of aresource for video broadcasting blocks these control messages and causessystem performance problems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates examples of a system architecture of a cellularwireless system.

FIG. 2 illustrates an example of sub-carriers and sub-channels.

FIG. 3 illustrates an example of time and frequency resources.

FIG. 4 illustrates three different types of video frames.

FIG. 5 illustrates video bursts along with a scheduling message pointingto their positions.

FIG. 6 illustrates different video burst patterns for a single videostream.

FIG. 7 illustrates different video-burst distributions for multiplevideo streams.

FIG. 8 illustrates an example of how a video burst and its video frameconfiguration change as the number of video streams increases.

FIG. 9 illustrates an example of FEC (Forward Error Correction) codingconfigurations with multiple video frames within a video burst.

FIG. 10 illustrates how AVBs (auxiliary video bursts) are used withtheir original video bursts.

FIG. 11 illustrates using an RF tuner to receive both video and data ina multiple frequency band system.

FIG. 12 illustrates a receiver with a single RF tuner in a multiplefrequency band system.

FIG. 13 illustrates a mobile station receiver in a broadcasting andcommunication system.

DETAILED DESCRIPTION

Methods and apparatus are disclosed herein for resource configuration ina cellular broadcasting and communication network of base stations andmobile stations. In this network a video stream can be transmitted froma base station to a mobile station as bursts of video and data framesare configured in a particular sequential manner. Special schedulingsignals are designed to efficiently announce video burst information tothe subscribing mobile stations, allowing the mobile stations to turn ontheir transceiver circuitry only when video bursts arrive. In a videoburst, the available data resources, in addition to video resources, areused to transmit data application packets and/or special controlinformation to the subscribing mobile stations. Methods and processesare also disclosed for a mobile station to use a single RF tuner withina system with multiple frequency bands.

The disclosed multiple access technology can be of any special formatsuch as Code Division Multiple Access (CDMA), Time Division MultipleAccess (TDMA), Frequency Division Multiple Access (FDMA), OrthogonalFrequency Division Multiple Access (OFDMA), or Multi-Carrier CodeDivision Multiple Access (MC-CDMA). Without loss of generality, OFDMA isemployed as an example to illustrate the present invention. The systemcan also be either time division duplex (TDD) or frequency divisionduplex (FDD).

The following description provides specific details for a thoroughunderstanding of the various embodiments and for the enablement of oneskilled in the art. However, one skilled in the art will understand thatthe invention may be practiced without such details. In some instances,well-known structures and functions have not been shown or described indetail to avoid unnecessarily obscuring the description of theembodiments.

The terminology used in the description presented below is intended tobe interpreted in its broadest reasonable manner, even though it isbeing used in conjunction with a detailed description of certainspecific embodiments of the invention. Certain terms may even beemphasized below; however, any terminology intended to be interpreted inany restricted manner will be overtly and specifically defined as suchin this Detailed Description section.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” Words using the singular or pluralnumber in this Detailed Description section also include the plural orsingular number respectively. Additionally, the words “herein,” “above,”“below” and words of similar import, when used in this application,shall refer to this application as a whole and not to any particularportions of this application. When the claims use the word “or” inreference to a list of two or more items, that word covers all of thefollowing interpretations of the word: any of the items in the list, allof the items in the list and any combination of the items in the list.

In order to minimize the power consumption of a mobile station, it isdesirable to deliver video broadcasting data within a short period oftime and fill up a video buffer of the mobile station (MS) so that itcan be played back later. This only requires the radio frequency (RF)and the base-band transceivers of the mobile station to be powered upduring the same short period. The rest of the time the transceiver canbe shut down; minimizing the power consumption. Implementing suchscheme, in a system with other types of data application, requiresharmonizing various applications and optimizing the results.

In one embodiment, to reduce the power consumption of a receiving mobilestation, a video stream is transmitted from a base station (BS) asbursts of video and data frames configured in a particular sequentialmanner. A mobile station can turn off its transmitting and receivingcircuits during the periods between the video bursts. In a video burst,the available data resources, in addition to video resources, are usedto transmit data application packets and/or special control information.Special scheduling signals are designed to efficiently announce videoburst information to the subscribing mobile stations.

A video broadcasting application is used as an example to illustratesome aspects of the invention. More generally, the disclosed methods andapparatus can be applied to other applications that use broadcasting ormulticasting and benefit from buffering data and playing it back to savepower. Examples are music/audio broadcasting and multicasting-based datadownloading. On the other hand, “data application” refers to otherapplications with non-broadcasting/multicasting nature, such as webaccess, voice over IP, and FTP.

Throughout the following specification, examples of a single frequencynetwork (SFN) are used to illustrate the applications of videobroadcasting; however, employing a SFN is not a requirement.

Cellular Broadcasting and Communication Systems

FIG. 1 depicts a typical wireless network 100, where there are aplurality of base stations (BS's) 101 each of which provides coverage toits designated area, normally called a cell 102. If a cell 102 isdivided into sectors, from system engineering point of view each sectoritself can be considered to be a cell. Therefore, the terms “cell” and“sector” are interchangeable in this context.

There is at least one control server 104 in a wireless network 100 forcontrolling one or multiple BS's 101. The control server 104 isconnected to the BS's 101 via the backbone network 106, which can beeither a wired network or a wireless network. The backbone network 106can also be either a circuit switched network or a packet switchednetwork. The backbone network 106 may connect to other servers in thesystem, such as a number of content servers 108, a number of networkmanagement servers 112, and/or a number ofauthentication/authorization/accounting (AAA) servers 110.

A BS 101 serves as a focal point to wirelessly distribute information toand collect information from its MS's 114, which are the communicationinterface between the users and the wireless network 100. Thetransmission from a BS 101 to an MS 114 is called a downlink and thetransmission from an MS 114 to a BS 101 is called an uplink. The term“MS” also can represent a user terminal in a fixed wireless system or aportable device with a wireless communication interface.

In wireless applications such as digital video broadcasting, the SFNtechnology is used to alleviate the problem of interference between BS's101. Using OFDM, BS's 101 simultaneously transmit the same broadcastingcontent while employing the same time/frequency resource. A receiver canthen combine the received signals from different BS's 101 to boost itsSNR (signal to noise ratio).

In the backbone network 106, the control server 104 coordinates thesynchronized video broadcasting. When video stream packets aredistributed from the control server 104 to the BS's 101, additionalsynchronization information is appended to the packets by a devicecalled Distribution Adapter (DA). The video packet distribution networkis built on top of the backbone network 106 via tunneling technologies.

For a video broadcasting packet, the BS 101 forwards the packet to aReceiving Adapter (RA), which extracts the synchronization information,and broadcasts the video simultaneously with other BS's 101.

Data application packets are transmitted to the BS 101 directly, withoutencapsulation, using tunneling protocols. The BS 101 separates dataapplication packets from video broadcasting packets by their destinationaddresses and other properties. Data application packets bypass RA andare transmitted to MS's 114 according to a scheduling by each individualBS 101.

Video Frames

The physical media resource (e.g., radio or cable) in a multi-carriercommunication system can be divided in both the frequency and timedomains. This canonical division provides a high flexibility and finegranularity for resource sharing. The building-blocks of multi-carriersignals in the frequency domain are sub-carriers, a fixed number ofwhich are within a particular spectral band or channel.

FIG. 2 depicts three types of sub-carriers, as follow:

-   -   1 Data sub-carriers 200, which carry information data;    -   2. Pilot sub-carriers, whose phases and amplitudes are        predetermined and are made known to all receivers, and which are        used for assisting system functions such as estimation of system        parameters; and    -   3. Silent sub-carriers, which have no energy and are used as        guard bands and DC carriers.

The data sub-carriers can be arranged in a particular manner into groupscalled sub-channels to support both scalability and multiple access. Thepilot sub-carriers are also distributed over the entire channel in apredetermined manner. The sub-carriers forming one sub-channel are notnecessarily adjacent to each other.

The building-blocks of multi-carrier signals in the time domain are timeslots to support multiple access. The resource division in both thefrequency and time domains is depicted in FIG. 3, where the radioresource is divided into small units in both the frequency and timedomains: sub-channels and time slots. The basic structure of amulti-carrier signal in the time domain is made up of time slots. A timeslot may contain one or multiple OFDM symbols. A “frame,” typically of afixed length (e.g., 5 ms), may contain one or multiple slots.

In a broadcasting and communication system with a frame structure, thevideo broadcasting application and the data application use differentair link resources. If SFN is used for the video broadcastingapplication, its reserved resource in a frame is called SFN videoresource. A frame containing a video resource is called a video frame;otherwise, it is called a data frame.

FIG. 4, while only illustrating the downlink, shows three differenttypes of video frames. The first type contains both video and dataresources. They are separated in the time domain using different OFDMsymbols. In the second type frame, the video resource and the dataresource are using different sub-carriers. The third type contains onlythe video resource.

A video broadcasting “stream” is defined as a stream for a particularvideo broadcasting program. For example, one stream carries CNN newschannel program, the other carries video broadcasting information fromFOX.

Each video stream is associated with a bit rate, which can be eitherfixed or variable. In order to support a certain bit rate, the number ofvideo frames per second is derived based on the calculations of thevideo resource capacity. As an example, a system with an 8-MHz wirelesschannel and a 5-ms frame is used herein to illustrate the disclosedembodiments. It is further assumed that the system is sampling at 10 MHzand using 1024-point FFT. This example of a system's effective bandwidthis comprised of 600 OFDM sub-carriers. Each symbol in the system lastsabout 100 ns; therefore, it has a total of 50 symbols within each frame.

In one embodiment, a frame is used either entirely or partially forvideo broadcasting. For example, the entire frame (all 50 symbols) isused for video broadcasting with 16QAM modulation and 1/2-rate coding,resulting in a frame capacity of 2×600×50=60K bits. With N video framesper second, the video stream bit rate is 60N Kbps. If a video streamrequires 240 Kbps throughput, a burst of 4 video frames every second isenough. In contrast, if only a part of the frame, for example sixsymbols, is used as video resource, with the same 16-QAM and 1/2 ratecoding, the video capacity per frame is 2×600×6=7.2K bits, in which casethe transmission of a 144-Kbps video stream requires 20 frames persecond.

Video Burst

A video burst is defined as a sequence of frames within a short periodof time. For one video stream, the duration between the two consecutivevideo bursts is relatively longer than the length of the video burstitself. To reduce the power consumption of a receiving MS 114, a videostream can be transmitted from the BS 101 as video bursts configured ina particular sequential manner with both video and data frames. Thetemporal location and the configuration of a video burst are announcedby a special message carrying the scheduling signal, wherein the specialmessage is broadcasted periodically.

FIG. 5 illustrates the relationship of video bursts 502 with thescheduling message 500. The video burst takes about 50 ms, with a gap of950 ms between two video bursts. The scheduling signal indicates thelocation of the video bursts as well as other control information. Theformat of the scheduling signal and its transmission mechanism isdiscussed below.

FIG. 6 illustrates three examples of “video burst patterns” for a singlevideo stream, where video burst patterns are the interleaving video anddata frames within a video burst. Different video burst patterns may beused, depending on the nature of the data applications. In the firstpattern, a video burst has five consecutive video frames. In the secondpattern the video burst has three video frames and, to mitigate thelatency impact on the data applications, there is a data frame betweenthe first and the second video frame and another data frame between thesecond and the third video frame. In this pattern the maximum latencybetween two neighboring data frames is only 5 ms, and the entire videoburst lasts 5×5=25 ms. In the third depicted pattern the video burst has4 video frames with a data frame between the second and the third videoframe. With this pattern, the maximum delay between two neighboring dataframes is 10 ms. The total video burst lasts 25 ms.

Transmitting a video stream by video bursts can reduce the powerconsumption of the receiving MS's 114. With such arrangement, each MS114 can turn on its RF and base-band circuit to receive a video burstand shut them down subsequently to save power for a relatively longperiod, until the arrival of a next burst. The video burst pattern andits schedule is announced to all the receiving MS's 114 using schedulingsignal. The video burst pattern for a video stream can be reconfiguredover time. The pattern change is also announced to all the receivingMS's 114 through the scheduling signal.

Within a video burst, the data frames and the data resource of the videoframes are called “available data resource.” In one embodiment, thesystem can use the available data resource in a video burst to performsecurity key update, establishing network connection, paging, locationupdate, resynchronization, or power control for the subscribing MS's114.

In another embodiment, an MS 114 measures the receiving signal qualityand collects statistics of the received video stream, such as the packeterror rate. The BS 101 allocates a resource from the available dataresource of the video burst for an MS 114 to report its CQI measurementand other statistics of the received video stream. When necessary, theMS 114 may be required to report which video stream it receives.

In yet another embodiment, since the receiving circuit in an MS 114 isturned on during its video burst, the BS 101 can notify the MS 114 aboutits newly arrived data application packets, using the available dataresource in the burst. The MS 114 can also send uplink data packets tothe BS 101 during the burst.

If there are only a small number of data application packets fordownlink and uplink, the BS 101 and MS 114 can complete the transmissionof data packets during a video burst. However, if the number of datapackets exceeds the capacity of the available data resource in a videoburst, the BS 101 and the MS 114 can coordinate to extend the power-onperiod to continue the data exchange.

Multiple Video Streams

FIG. 7 depicts an embodiment wherein multiple video streams aretransmitted with their own video bursts. The bursts associated withdifferent video streams are evenly distributed, next to each other oroverlapping/interleaving with each other. In the first example, Videoburst 1 and Video burst 2 are evenly distributed over time. In thesecond example, Video burst 1 and Video burst 2 are next to each other.In the third example, Video burst 1 and Video burst 2 are overlapped andinterleaved with each other.

In some systems, the number of supported video streams can change overtime, which affects the video burst pattern and its distribution in thetime domain. The video broadcasting resource in a system can beincreased by:

-   -   1. increasing the number of video frames, while keeping the        video burst pattern unchanged;    -   2. changing the video burst pattern so it contains less data        frames; and/or    -   3. increasing the video resource in each video frame, which also        affects the video burst pattern.

FIG. 8 shows a number of system configuration transitions to increasevideo capacity. First, the data frames between video bursts in theconfiguration 800 are displaced by new video bursts in the configuration802. Next, the data frames within the video bursts in configuration 802are removed to reallocate resource to new video bursts in configuration804. Finally, the video resource within the video frame increases from7.2 Kbits in configuration 804 to 10.8 Kbits in configuration 806.

In one embodiment, in order to meet the video throughput demand as thenumber of video streams increases, the system replaces data frames withvideo frames to form video bursts. The video bursts for different videostreams are still transmitted sequentially, possibly with some dataframes in between.

In another embodiment, the video burst pattern for a particular videostream is configured in accordance with the overall video throughputdemand. As the number of video streams increases, a video bursts patternis changed into more video centric (i.e., the burst contains fewer dataframes). On the other hand, as the number of video streams decreases, avideo bursts pattern is changed into less video centric.

In yet another embodiment, the video resource in each video frame isadjusted to meet the video throughput demand. In a video frame, thevideo resource is augmented by displacing the data resource, either inthe time domain or the frequency domain. In a TDD system, the uplinkperiod in the video frame is also reduced if necessary, therebyincreasing the downlink video/data resource.

Video Burst Scheduling Signal

In some embodiments the video burst schedule is announced to thesubscribing MS's 114. In one embodiment, the video burst schedule isbroadcasted periodically at a fixed time and frequency, either in avideo frame or in a data frame. An MS 114 that loses the synchronizationto the video burst can resynchronize to the burst sequence by decodingthe scheduling information. If the video burst schedule changes, all theMS's 114 are to be notified at the earliest possible opportunity.

In another embodiment, the scheduling signal is transmitted in specialresource regions. For example, a special message carrying the schedulingsignal appears once every 10 seconds in the first data frame.Alternatively, the scheduling signal is transmitted using the firstsymbol of the video resource in the first video frame of a video burst.

In yet anther embodiment, a frame (sequence) number, which is known toall the control servers is used to represent a synchronized network timeby being associated with a common time reference such as the GPS. Such atime reference is also critical to SFN operation. A modular number,instead of the absolute sequence number may be used to reduce theoverhead of indicating the frame number.

The video burst scheduling signal may include the following controlinformation for each video stream:

-   -   1. the frame number where each video burst starts;    -   2. the length of each video burst;    -   3. the pattern of each video burst;    -   4. the video resource region in each video frame of each video        burst; and/or    -   5. the coding and modulation scheme for each video burst.

In one embodiment, some scheduling information is reduced or omitted oris broadcasted less frequently when it is already known, implied,inferred, or redundant. For example, if the video bursts of a videostream are broadcasted periodically and regularly and the video burstpattern remains unchanged, the scheduling signal is sent outinfrequently, for example, once every 10 seconds. This greatly reducesthe overhead of scheduling signals.

In another embodiment, to save the air link resource, the scheduleinformation is compressed using a certain technique or be representedvia a certain format. In particular, a finite set of video-burstpatterns is predefined in the system. The mapping between the videoburst patterns and their corresponding pattern indices is broadcasted ina message to all the MS's 114. The pattern index is used to indicate thepattern for each video burst. The mapping is implemented, for example,as in the table shown below:

Pattern Index Pattern Format 0 VDVDVDV 1 VVDVV

Alternatively, the video burst pattern is expressed in the video burstscheduling signal using bitmap format. A bit of “1” stands for videoframe and a bit of “0” stands for data frame or vice versa.

In yet another embodiment, a number of video streams are supported inthe system. The mapping between the stream index and its associatedvideo burst scheduling information is implemented, for example, as inthe table shown below:

Stream Index Associated Scheduling Information  1 Start frame number: 20Length of the video burst: 7 Video burst pattern bitmap: 0x55(01010101B) Start symbol No. for video resource: 2 Number of symbols forvideo resource: 8 MCS index for the video resource: 2 (QPSK ½ coding)  2Start frame number: 40 Length of the video burst: 5 Video burst patternbitmap: 0x15 (00010101B) Start symbol No. for video resource: 0 Numberof symbols for video resource: 6 MCS index for the video resource: 4(16QAM ½ coding) . . . . . . 10 Start frame number: 180 Length of thevideo burst: 7 Video burst pattern bitmap: 0x55 (101010101B) Startsymbol No. for video resource: 1 Number of symbols for video resource:12 MCS index for the video resource: 2 (QPSK ½ coding)

In addition, an application layer message announces the content of thevideo stream associated with its index, as shown in the following table.Some of the content information, such as the channel and program names,can be used in a video program menu for the user. When a user selects achannel from the menu, the corresponding stream index signals the MS 114to find the corresponding scheduling information for the video stream.

Stream Channel Index Name Program Name  1 FOX The Simpsons  2 CNN NewsUpdate . . . . . . . . . 10 ESPN Sports Update

Forward Error Correction for Video Burst

In one embodiment, the FEC (Forward Error Correction) coding blockcomprises information bits from multiple consecutive video frames withina video burst. Coding across video frames can increase time diversityand therefore improve the performance over fading channels.

FIG. 9 illustrates the FEC coding configurations with multiple videoframes within a video burst. A coding block in Video burst 1 may consistof bits from two neighboring video frames and a coding block in Videoburst 2 may comprise bits concatenated across three neighboring frames.

Auxiliary Video Burst

When additional transmission capacity in either the time or thefrequency domain is available, auxiliary video bursts (AVBs) may be usedto deliver additional information to enhance video broadcast signals.

In one embodiment, an AVB is transmitted in a redundant form of theoriginal video burst. An AVB can be a simple replica of a video burstitself and when an MS 114 receives the auxiliary video burst, itcombines it with its original, using the Chase combining technique, todecode the video signals. An AVB can also carry incremental redundancyinformation of a video burst. In such a case, the MS 114 fuses theincremental redundancy information to the original video burst, using apredetermined algorithm, to decode the video signals. An MS 114 canelect to receive the video information in the AVB if an error has beendetected in the original video burst. The announcement of the schedulinginformation should include additional information regarding theretransmission.

In another embodiment, an AVB is used to transmit additional videoinformation to improve the video quality. An AVB can be transmitted bythe individual BS 101 using multicasting. The BS 101 stores theadditional video broadcasting information locally and, if the situationpermits (e.g., light local traffic or additional bandwidth available),transmits them as the auxiliary video bursts. The BS 101 is responsiblefor announcing the scheduling information.

FIG. 10 shows an example of the use of AVBs. The MS 114 receiver willjointly decode V1 and V1′ using an incremental redundancy algorithm. Inthe case where V2′ is a repetition of V2, the MS 114 receiver uses, forexample, the Chase combining algorithm to decode.

Designs for a System with Multiple Frequency Bands

In one embodiment frequency-switch methods and processes are used in asystem with multiple frequency bands such that only one RF tuner isneeded in the receiving MS 114. A single RF tuner implies that thereceiver, regardless of its number of branches, operates in one singleRF frequency. For example, some MS's 114 may have multiple branches intheir receivers to implement a type of multiple antenna technology, suchas diversity combining or multiple-input-multiple-output (MIMO)techniques, but they are referred to as one-RF-tuner receivers.

In another embodiment, when an MS 114 is to switch from a video streamin one frequency band to another video stream in a different frequencyband, it triggers the inter-frequency handoff process. Triggering theinter-frequency handoff process hands off the data applicationassociated with the original video stream to be in the switchedfrequency band.

In yet another embodiment, the data application continues to use thesame frequency band when the video stream is switched to anotherfrequency band. The BS 101 scheduler tracks the video frame for each MS114 and makes resource allocation to avoid simultaneous delivery of thevideo stream in the video frequency band and other application data in adifferent data frequency band. The controller in the MS 114 receiverwill switch from its data frequency band to video frequency band whenits video frame arrives.

In yet another embodiment, when inter-frequency handoff for dataapplication is required, the data application is switched to anotherfrequency channel but the video stream continues transmitting in theoriginal frequency band. The BS 101 scheduler tracks the video frame foreach MS and makes resource allocation to avoid simultaneous delivery ofthe video stream in the video frequency band and other application datain a different data frequency band. The controller in the MS 114receiver will switch from its data frequency band to video frequencyband when its video frame arrives.

In still another embodiment, the system dedicates multiple frequencybands for the video broadcasting application and multiple frequencybands for other applications such as data. In this case an interleavingvideo frame pattern, called mixed video burst pattern, is used. Themixed video burst pattern will have video frames of different streamsinterleaved with each other, such as V1-V2-V1-V2-V1-V2. With thisconfiguration, the controller in the MS 114 receiver will switch fromits data frequency band to video frequency band when its video burstarrives. The BS 101 scheduler tracks the video frame for each MS 114 andmakes resource allocation to avoid simultaneous delivery of the videostream in the video frequency band and other application data in thedata frequency band.

FIG. 11 shows two examples of using one RF tuner to receive both videoand data in a multiple frequency band system. In the first example, boththe video and date applications are in a same frequency band. Whenswitching to another video frequency band is requested, the MS 114triggers the inter-frequency handoff process. In the second example, thevideo and data transmissions are carried out in different frequencybands. The controller in the receiver handles the switching betweendifferent frequency bands. The arrows in FIG. 11 indicate how thecontroller should switch between the frequency bands.

FIG. 12 illustrates a receiver with a single RF tuner in a multiplefrequency band system. The receiver stores, in its memory 1204, thesynthesizer information and the previous channel information for bothvideo frequency band and data frequency band. Based on schedulinginformation, a controller 1206 determines the switch point between thesetwo frequency band configurations. Once the controller switches to thevideo frequency band configuration, it applies the control informationto the mixer 1200 and the base-band processor 1202.

Receiving Operation

In a typical scenario, a user subscribes to a video broadcastingprogram, which corresponds to a particular video stream. The contentprovider and the network service provider will authenticate the requestand admit the access by assigning to the MS 114 the key information aswell as the video burst scheduling information.

In one embodiment, an MS 114 turns on its receiving and transmittingcircuit(s) during its subscribed video bursts and turns off itscircuit(s) during the periods in between video bursts. The receivedvideo burst is decoded and stored in a video buffer and is later playedback on the display.

In another embodiment, an MS 114 with a single RF tuner operates withina multiple-frequency-band system and its controller switches andsynchronizes to the data frequency band or the video frequency band whena data frame or a video frame arrives, respectively.

FIG. 13 illustrates an MS 114 receiver in a broadcasting andcommunication system. After the RF transceiver 1300 and base-band 1302processing, the packets belonging to video broadcasting application arefirst stored in a video buffer 1310 and, after video decoding 1312, areplayed back on the video display 1314. Other data application packetsare processed along a separate path by the data processing unit 1304. Acontrol unit 1308 controls the RF transceiver 1300, base-band processor1302, and the operation of the video processing units 1306.

The above detailed description of the embodiments of the invention isnot intended to be exhaustive or to limit the invention to the preciseform disclosed above or to the particular field of usage mentioned inthis disclosure. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. Also, the teachingsof the invention provided herein can be applied to other systems, notnecessarily the system described above. The elements and acts of thevarious embodiments described above can be combined to provide furtherembodiments.

All of the above patents and applications and other references,including any that may be listed in accompanying filing papers, areincorporated herein by reference. Aspects of the invention can bemodified, if necessary, to employ the systems, functions, and conceptsof the various references described above to provide yet furtherembodiments of the invention.

Changes can be made to the invention in light of the above “DetailedDescription.” While the above description details certain embodiments ofthe invention and describes the best mode contemplated, no matter howdetailed the above appears in text, the invention can be practiced inmany ways. Therefore, implementation details may vary considerably whilestill being encompassed by the invention disclosed herein. As notedabove, particular terminology used when describing certain features oraspects of the invention should not be taken to imply that theterminology is being redefined herein to be restricted to any specificcharacteristics, features, or aspects of the invention with which thatterminology is associated.

In general, the terms used in the following claims should not beconstrued to limit the invention to the specific embodiments disclosedin the specification, unless the above Detailed Description sectionexplicitly defines such terms. Accordingly, the actual scope of theinvention encompasses not only the disclosed embodiments, but also allequivalent ways of practicing or implementing the invention under theclaims.

While certain aspects of the invention are presented below in certainclaim forms, the inventors contemplate the various aspects of theinvention in any number of claim forms. Accordingly, the inventorsreserve the right to add additional claims after filing the applicationto pursue such additional claim forms for other aspects of theinvention.

We claim:
 1. A receiving method for a mobile station in a multi-cellwireless system using a frame structure, each frame containing aplurality of orthogonal frequency division multiplexing (OFDM) symbols,the method comprising: receiving a sequence of consecutive frames, thesequence of consecutive frames comprising a plurality of first framesand a plurality of second frames that are intermixed in accordance withan intermixing configuration pattern, each of the first framescontaining time-frequency resources used for content multicasting orbroadcasting (MB) via a single frequency network (SFN) that is comprisedof base stations in multiple cells transmitting the same MB contentusing OFDM and employing a same time and frequency resource, and each ofthe second frames containing time-frequency resources used for dataunicasting without the use of a SFN; receiving a scheduling signalcontaining a bit-map that indicates the intermixing configurationpattern of the received first and second frames by using “1” in thebit-map to represent a first frame and a “0” in the bit-map to representa second frame, or a “1” in the bit-map to represent a first frame and a“0” in the bit-map to represent a second frame; and utilizing thereceived bit-map to identify the first and second frames.
 2. The methodof claim 1, further comprising receiving a scheduling signal containinginformation indicating a start frame number for the sequence ofconsecutive frames.
 3. The method of claim 1, further comprisingreceiving a scheduling signal containing an index indicating amodulation and coding scheme (MCS) used for a SFN time-frequencyresource.
 4. The method of claim 1, further comprising receiving ascheduling signal containing information indicating a length of thesequence of consecutive frames.
 5. The method of claim 1, furthercomprising receiving a scheduling signal containing an MB stream index.6. The method of claim 1, wherein each of the first frames contains afirst region and a second region, the first region preceding the secondregion in time, wherein: the first region is used for data transmissionwithout the use of SFN (non-SFN) and the first region comprises a firstnumber of OFDM symbols, wherein the first number applies to each of thefirst frames; and the second region is used for MB via SFN (MBSFN) andthe second region comprises a second number of OFDM symbols, wherein thesecond number applies to each of the first frames.
 7. The method ofclaim 6, further comprising receiving a scheduling signal containing anindication identifying the first region or the second region in each ofthe first frames.
 8. The method of claim 6, wherein the first number is0, 1, or
 2. 9. The method of claim 6, wherein the second number is 6, 8or
 12. 10. The method of claim 1, wherein the bit-map contains between 2and 8 bits.
 11. The method of claim 1, wherein the first frames furthercontain time-frequency resources used for data transmission without theuse of a SFN (non-SFN) and the receiver is further configured to receivedata application packets, instructions for performing control functions,or both data application packets and instructions for performing controlfunctions in the second frames or in the non-SFN time-frequencyresources in the first frames.
 12. The method of claim 11, wherein thecontrol functions include security key updating, establishing networkconnections, paging, providing location updates, facilitatingresynchronization, enabling power control, providing notification ofdata packet arrival, sending uplink data packets, providing channelquality information, or providing statistics on a packet error rate. 13.The method of claim 1, wherein the MB content comprises video, audio, ordata.
 14. The method of claim 1, wherein the reception employsorthogonal frequency division multiple access (OFDMA) or frequencydivision multiple access (FDMA); and Time Division Duplexing (TDD) orFrequency Division Duplexing (FDD) technique.
 15. A mobile station in amulti-cell wireless system using a frame structure, each framecontaining a plurality of orthogonal frequency division multiplexing(OFDM) symbols, the mobile station comprising: a receiver configured toreceive: a sequence of consecutive frames, the sequence of consecutiveframes comprising a plurality of first frames and a plurality of secondframes that are intermixed in accordance with an intermixingconfiguration pattern, each of the plurality of first frames containingtime-frequency resources used for content multicasting or broadcasting(MB) via a single frequency network (SFN) that is comprised of basestations in multiple cells transmitting the same MB content using OFDMand employing a same time and frequency resource, and each of the secondframes containing time-frequency resources used for data unitcastingwithout the use of a SFN; and a scheduling signal containing a bit-mapthat indicates the intermixing configuration pattern of the receivedfirst and second frames by using “1” in the bit-map to represent a firstframe and a “0” in the bit-map to represent a second frame, or a “1” inthe bit-map to represent a first frame and a “0” in the bit-map torepresent a second frame; and a transmitter configured to transmit datapackets using time-frequency resources.
 16. The mobile station of claim15, wherein the receiver is further configured to be enabled during someframes and disabled during other frames.
 17. The mobile station of claim15, wherein the receiver is further configured to receive a schedulingsignal containing information indicating a start frame number for thesequence of consecutive frames.
 18. The mobile station of claim 15,wherein the receiver is further configured to receive a schedulingsignal containing an index indicating a modulation and coding scheme(MCS) used for a SFN time-frequency resource.
 19. The mobile station ofclaim 15, wherein the receiver is further configured to receive ascheduling signal containing information indicating a length of thesequence of consecutive frames.
 20. The mobile station of claim 15,wherein each of the first frames contains a first region and a secondregion, the first region preceding the second region in time, wherein:the first region is used for data transmission without the use of SFN(non-SFN) and the first region comprises a first number of OFDM symbols,wherein the first number applies to each of the first frames; and thesecond region is used for MB via SFN (MBSFN) and the second regioncomprises a second number of OFDM symbols, wherein the second numberapplies to each of the first frames.
 21. The mobile station of claim 20,wherein the receiver further receives a scheduling signal containing anindication identifying the first region or the second region in each ofthe first frames.
 22. The mobile station of claim 15, wherein thereceiver is further configured to separate data packets and MB contentpackets, wherein data packets are input to a data processing unit and MBcontent packets are stored in a buffer.
 23. The mobile station of claim15, the mobile station further comprises a video decoder and a videodisplay unit.